Control for range heat



p 5, 1939- I E. K. QLARK 2,172, 189

CONTROL FOR RANGE HEAT Filed March 13, 1937 WITNESSES:

Patented Sept. 5, 1939 PATENT OFFICE CONTROL FOR RANGE HEAT Earl K. Clark, Mansfield, Ohio, assignor to Westinghouse Electric & Manufacturing Company,

East Pittsburgh, Pa.,

sylvania Application March 13,

18 Claims.

My invention relates to range surface heaters and more particularly to current control for such surface heaters.

In ranges now known to the art, the operations of the surface heaters have been limited to the conventional low, medium and high heat positions. This limitation has seriously restricted the proper advancement of the electric range in view of the large number of heat positions available on gas ranges. It is, therefore, an object of my invention to remove this limitation by providing means whereby the surface heaters of an electric range may be adjusted to a large number of heat positions.

A further object of my invention is to provide a common means forvarying the operation of a thermally responsive circuit-controlling device and for operating a'manually operated circuitcontrolling device.

A further object of my invention is to provide a combined circuit-controlling device which may be used in conjunction with either a twoor a threewire power source.

A further object of my invention is to provide a rugged, simple, compact, inexpensive circuit-controlling device which will be small enough to enable it to be placed upon the present electric ranges without increasing the size thereof.

Other objects of my invention will either be 30 pointed out specifically in the following description of a preferred form of my invention, or will be apparent from such description.

In the accompanying single sheet of drawings:

Figure 1 is a side elevation and partial sectional view of a device embodying my invention;

Fig. 2 is a sectional View taken along line II-II of Fig. 1;

Fig. 3 is a wiring diagram of a three-wire surface heater in conjunction with my device;

Fig. 4 is a wiring diagram of a two-wire surface heater in conjunction with my device;

Fig. 5 is a diagram illustrating the relative positions of the control shaft to the power output of the three-wire surface heater;

Fig. 6 is a diagram illustrating the relative positions of the control shaft to the power output of the two-wire surface heater;

Fig. 7 is a side elevational and partial sectional View of a device similar to that shown in Fig. 1 with an ambient temperature compensator incorporated therewith;

Fig. 8 is a sectional view taken along line VIIIVIII of Fig. '7; and

Fig. 9 is a fractional View of a modification of the structure shown in Fig. 1.

a corporation of Penn 1937, Serial No. 130,720

Referring to Figure 1, I show a range surface heater or circuit-controlling mechanism H comprising a casing l, a manually operable circuitcontrolling device 2'!, a thermally responsive circuit-controlling device -2l, a range heater unit 35-36, and a manually rotatable control shaft is having a plurality of cams l0 and I2 operatively associated therewith for operating the said manually operated circuit-controlling device 27 and adjusting the thermally responsive circuit-controlling device 20-2I, whereby the output of the range surface heater, or the like, may be controlled and regulated.

The casing I may be made in any shape and of any material desired; however, it is preferred that it be composed of sheet steel and of a fabricated construction.

The manually operable circuit-controlling device 2-'l may comprise a flexible finger 2 and a semi fiexible finger 7. The semi-flexible finger I may be insulatedly attached to housing I by means of an insulating tube 8, a bolt 5 and a nut 6. Located on the free end of finger I is a contact 3 which may be composed of any suitable material. Flexible finger 2 is insulatedly mounted on casing I in a manner similar to finger 1 by means of the insulating tube 8, bolt 5 and nut 6. This finger 2 has a contact 4, similar in material to contact 3, located on the free end thereof. The contacts 3 and 4 thus become operatively associ ated, functioning as a circuit-maker and breaker.

The thermally responsive circuit-controlling device 262l comprises a bimetallic finger 20 and a radiant heater 2|. Located on the free end of bimetallic finger 20 is a contact 22 which may be operatively associated with stationary contact 23. Contact 23 may be rigidly and insulatedly mounted to the casing l by means of an insulating tube 30, a bolt 26 and a nut 28. Operatively associated at the rigid end of the bimetallic finger 20 is a suitable irregularly shaped connecting device 3i which has attached to its free end the radiant heater 2i. This radiant heater is permanently attached at its other end to a suitable bracket which may be insulatedly attached to casing I by means of an insulating tube 24, a bolt 21 and a nut 29.

The bimetallic finger 20 and radiant-heater supporting device 3| are rigidly attached to a bellcrank lever 14 by means of rivets l6. Suitable insulating material [5 may be inserted between the bell crank lever l4 and the rivets l6, and the bimetallic finger 20 and the radiant-heater supporting device 3| to insulate the bimetallic finger and radiant heater from bell-crank lever I4.

Bell-crank lever l4 may be swingably mounted on casing l by means of any suitable hinging device 33 which may be rigidly attached to said casing, permitting the bimetallic finger 20, which is insulatedly mounted thereto, to be bodily moved therewith.

Operatively associated with the free end of bell-crank lever 14 and with flexible finger 2 are a plurality of cams l0 and i2, respectively. The cams l0 and I: may be attached to a control shaft 13 in any suitable manner. Cam l0 contacts the flexible finger 2 intermittently, while cam l2, which is circular, is permanently in contact with the U-shaped end of bell-crank lever It. Accordingly, due to the rotation of control shaft l3 and operatively associated eccentrically mounted cam [2, the bell-crank lever will be swung through a small arc, the effect of which is to bodily move the bimetallic finger and change the effective angular position of the bimetallic finger 20. This changing of the effective angular position of bimetallic finger 2G regulates the operating temperature thereof; namely, the greater the effective angle from a horizontal position the higher the operating temperature of said thermal responsive circuit-controlling device, and the smaller the effective angle from a horizontal position, the lower the operating temperature of said device.

Accordingly, by the rotation of the control shaft l3 and the operatively associated bell-crank M, the inherent operating characteristics of the bimetallic finger 20 may be adjusted to cause the bimetallic finger 20 and the operatively associated circuit-controlling device 2223 to operate at any desired temperature. Likewise, as the control shaft I3 is rotated, cam I0 is rotated and as the high point of said cam approaches the flexible finger 2, the said finger is forced upwardly, so that contact 4 engages contact 3. With a slightly greater rotation of the shaft l3 in either direction, the contact 4 will disengage itself from contact 3 due to the spring action of the flexible finger 2. It is, therefore, obvious that the rotation of control shaft 13 operates both the manually operated circuit-controlling device 2-! and the thermal responsive device enabling the surface heater to be controlled in a manner to be described hereinafter.

In operating the surface-heater-controlling device l in conjunction with a range or the like, while using a three-wire supply circuit therefor, one of the outside supply lines 32 may be connected to the semi-flexible finger T by means of a terminal IS. The other outside wire 34 may be connected to the stationary contact 23 of the thermally responsive circuit-controlling device 292l by means of a terminal H3. The neutral or middle wire 31 of the three-wire supply will then be connected to the mid-point of the surface heater, as shown in Figs. 1 and 3. The radiant heater 2| is then connected to one end of the surface heater or the like by means of terminals I! and bracket 25, the other terminal of the surface heater being likewise connected to the flexible finger 2 by means of a terminal 9.

If a power supply switch (not shown) be closed, so that suitable current fiows through section 36 of the surface heater, and the surface-heatercontrolling device ll be in the position shown in Fig. l, the radiant heater 2| after a predetermined increment of time will cause the bimetallic finger 20 to move to an open position, disengaging the contact 22 from the stationary contact 23, which will disconnect the surface heater from the power supply. Then as the radiant heater 2| cools, the bimetallic finger 20 will fiex to its original position causing the contact 22 to re-engage the contact 23 and permit a flow of current through section 33 of the surface heater as in its original position. The operating temperature of the bimetallic finger 20 may be regulated by the rotation of the control shaft I3 and operatively associated bell-crank lever M to any desired value. Accordingly, the bimetallic finger 20 and operatively associated radiant heater 2i due to the intermittent operation thereof will maintain the average power output of the surface heater at the value desired by the operator.

Should the control shaft l3 be rotated in a slightly clockwise direction from that shown in Fig. 1,:the contact 4 will engage contact 3 causing section 35 of the surface heater to be connected to the power supply. In such a position the bimetallic finger 20 is adjusted to remain closed a maximum length of time so that the surface heater is then in a high-heat position.

Should the control shaft l3 then be rotated in either direction, the operatively associated cam ID will cause the contact 4 to become disengaged from contact 3, disconnecting section 35 from the power supply. The radiated heat of the surface heater will then be reduced from the high position to the medium position. Then upon continuing the rotation of the control shaft IS in the same direction, the cam I2 will cause bell-crank lever 44 to reduce the flexure angle of the bimetallic finger 20 so that the bimetallic finger will continue to remain in the closed position a shorter length of time for every degree of rotation of said shaft l3, Should the shaft l3 be rotated approximately 180 from the position shown in Fig. l, the bimetallic finger 20 would then remain in a closed position a minimum length of time, which would correspond to the simmering or lowest heat output of the surface heater.

It is, therefore, obvious that the rotation of control shaft l3 regulates the operation of bimetallic finger 20 in such a manner that the power output of the surface heater may be of any value desired between its low or simmer position and its medium position, whereas, after a continued rotation of the control shaft toward the high setting thereof, the flexible finger 2 is swung upwardly causing contact 4 to become engaged with contact 3 resulting in the surface heater being in its high position. The direction of rotation of control shaft l3 at any position in the operation thereof is an arbitrary factor, since the cams may be so designed that the controlling device may be operated in either direction.

In using the surface-heater-controlling mechanism H with a two-wire power supply source shown in Fig. 4, the wires 32 and 34 may be connected to the controlling device in a manner described hereinbefore. The sections 35 and 36 are then in series relation with each other forming section 39, the thermally operated circuitcontrolling mechanism l l and the power supply. The only difference in operation with this type of connection over that of the three-wire is that the surface heater controlling mechanism is variably controlled by the control shaft l3 throughout its complete cycle of operation.

Since the manually operated circuit-controlling device 2-? is connected in series with the thermally responsive circuitcontrolling device 2fl-2l, the cam l0 must be built in reverse re- 30,1. IZLOU lation to its previous configuration and rotated substantially on shaft I3, as shown in Fig. 9, so that, as the heat responsive device 20-2l arrives at its lowest operation position, the cam ill with a slight continued rotation will permit contact 4 to disengage itself from contact 3, the contacts being closed at all other times. The high point of cam ID, as illustrated in Fig. 1, will be reduced to a radius equivalent to that of the previous normal or low portion of the cam and the previous low portion will be increased to a radius equivalent to the high point of cam [0 in Fig. 1, all as illustrated in Fig. 9. This construction will permit the controlling mechanism If to operate with the previous location of the manually operated circuit-controlling device 2! by merely changing the shape of cam l0. Consequently, as the heat responsive device 20-2l arrives at its lowest operating temperature, the cam will open the manually operated circuitcontrolling device 2-1, interrupting the circuit.

It is, therefore, obvious that the circuit-controlling mechanism may or may not be used in combination with a power switch and that the mechanism may be used with either a two or a three-wire supply to adjust the power output of a surface heater of an electric range, or the like, to an infinite number of heat positions.

It is to be understood that radiant heater 21 need not be connected in series with the surface heater, but may be connected in parallel therewith substantially as shown in Fig. '7, or in any manner desired. By using a shunt or potential radiant heater, it would be permissible to use the control device in conjunction with any wattage surface heater desired, whereas, with a series heater, as shown in Fig. 1, a different radiant heater element 2| is needed for every different size of surface heater.

If the manually operated circuit-controlling device 2'! be eliminated, the control mechanism If will then become a manually adjustable thermostat in which the bimetallic fingers operating temperature will be adjusted by changing the effective angular position of such finger. As hereinbefore stated, the greater this effective angle from the normally closed position of said bimetallic finger the greater will be the operating temperature of such thermostat. Conversely, with a smaller effective angle the thermostat will operate at a correspondingly lower temperature.

Referring to Figs. '7 and 8, I show a device, similar to that shown in Fig. 1, with an ambient temperature compensator operatively associated therewith. The bell-crank lever l4 may be swingably attached to casing l by means of a fulcrum pin 49 which may be rigidly attached to the casing by means of a bracket 43 or in any other suitable manner. The bell-crank lever l4 may have an extension 42 associated with the free end thereof. This extension 42 may extend outside the casing l and may have a bimetallic compensating member 46 rigidly attached to the free end thereof. A floating bracket 41 may be swingably mounted upon the fulcrum pin 49 and may have rigidly attached thereto the free-end of bimetallic compensator 42 and the rigid end of bimetallic finger 20. The swinging movements of bell-crank lever M will then be transmitted to the bimetallic finger 20 through the extension 42, bimetallic compensator 46, and floating bracket 41. The radiant heater 2| may be rigidly attached to the casing l at both ends by bracket 25, bolt 21, nut 29 and insulating tube 24, and

may be operatively associated with the heating units 35 and 36 by means of terminals l1, substantially as shown in Fig. 7.

The bimetallic compensator 4B is operatively mounted in reverse position to the bimetallic finger 20 and in a position such that the radiated heat from the radiant heater will not affect the operation thereof. Therefore, since the bimetallic compensator, which may be outside casing I, does not receive heat from the radiant heater 2 I, the curvature thereof will change only with changes in the ambient temperature, whereas the curvature of the bimetallic finger 20, which is inside casing I, will change with the variations of heat from the radiant heater 2i. In such a manner, the output of the range surface unit, regulated by the surface heater control, will be maintained at a substantially constant value regardless of the ambient temperature fluctuations.

In operating my device having an ambient temperature compensator thereon, the bell-crank lever I4 is swung through a small are by means of eccentrically mounted cam l2 as hereinabove described. As the bell-crank lever 14 swings through a small arc, the ambient temperature compensator is likewise swung through a small are, which in turn changes the effective angle of the bimetallic finger 20. It is, therefore, obvious that with a constant ambient temperature, the combination of bimetallic finger 20 and ambient temperature compensator 46 functions as a single member, the operation of which is controlled by means of radiant heater 2|. However, with a change in ambient temperature, the ambient temperature compensator will assume a reverse curvature to that of the bi metallic finger 20 with an increase or decrease in temperature and will cause the effective angle of the bimetallic finger 20 to be correspondingly changed to compensate for the change in the ambient temperature. Therefore, the effective position of the contacts at that free end of the bimetallic finger 20 will operate with a different frequency for every different ambient temperature which, in turn, will maintain a constant heat output of the range surface heater for every particular setting of the control device.

It is to be understood that various other applications and modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and the appended claims.

I claim as my invention:

1. In combination, a thermal responsive circuit-controlling device, a manually operable circuit-controlling device, means for adjusting said thermal device and means for actuating said manual device, said means having a common operating means.

2. In combination, a thermal responsive circuit-controlling device, a manually operable circuit-controlling device, rotatable means for adjusting said thermal device and rotatable means for actuating said manual device, said means having a common operating shaft.

3. In combination, a thermal responsive circuit-controlling device, a manually operable circuit-controlling device, cam means for adjusting said thermal device and cam means for actuating said manual device, said means having a common cam shaft.

4. In combination, a thermal responsive circuit-controlling device, a manually operable circuit-controlling device, and means comprising a plurality of cams respectively operatively associated with the thermal responsive circuitcontrolling device for adjusting the same and operatively associated with the manually\oper able circuit-controlling device for operating the same.

5. In combination, a thermal responsive circut-controlling device, a manually operable circuit-controlling device, a base therefor, a bellcrank lever swingably mounted on said base, means comprising the bell-crank lever for varying the operation of said thermal responsive circuit-controlling device, and means operatively associated with the manually operable circuitcontrolling device for operating said device.

6. In combination, a thermal responsive circuit-controlling device, a manually operable circuit-controlling device, a base therefor, a control shaft rotatabl mounted upon said base, a bellcrank lever swingably mounted on said base and operatively associated with the control shaft, means comprising the bell-crank lever and operatively associated control shaft for varying the operation of said thermal responsive circuit controlling device, and means operatively associated with the control shaft for operating said manually operable circuit-controlling device.

'7. In combination, a thermal responsive circuit-controlling device, a manually operable circuit-controlling device, a base therefor, a control shaft rotatably mounted upon said base, a plurality of cams attached to the control shaft, a bell-crank lever swingably mounted on said base and operatively associated with one of said cams, means comprising the bell-crank lever, the operatively associated cam and the control shaft for varying the operation of said thermal responsive circuit-controlling device, and means operatively associated with the control shaft for operating said manually operable circuitcontrolling device.

8. In combination, a thermal responsive circuit-controlling device, a manually operable circuit-controlling device, a base therefor, a control shaft rotatably mounted upon said base, a plurality of cams attached to the control shaft, a bell-crank lever swingably mounted on said base, said bell-crank lever being mounted intermediate the ends thereof and operatively associated at one end with one of said cams and rigid- 1y attached to the other end to said thermal responsive circuit-controlling device, means comprising the bell-crank lever, the operatively associated cam and the control shaft for varying the operation of said thermal responsive circuitcontrolling device, and means operatively associated with the control shaft for operating said manually operable circuit-controlling device.

9. In combination, a thermal responsive circuit-controlling device, a manually operable circuit-controlling device, a base therefor, a control shaft rotatably mounted upon said base, means operatively associated with the control shaft for operating said manually operable circuit-controlling device, and means operatively associated with the thermal responsive circuitcontrolling device for varying'the operation of said device.

10. In combination, a thermal responsive circuit-controlling device, a manually operable circuit-controlling device, a base therefor, a control shaft rotatably mounted upon said base, a plurality of cams rigidly attached to the control shaft, means comprising one of the cams for operating said manually operable circuit-controlling device, and means operatively associated with the thermal responsive circuit-controlling device for varying the operation of said device.

11. In combination, a thermal responsive circult-controllinggdevice, a manually operable circuit-controlling device, a base therefor, a control shaft rotatably mounted upon said base and means operatively associated with the control shaft for operating said manually operable circuit-controlling device and for varying the operation of said thermal responsive circuit-controlling device.

12. In combination, a thermal responsive circuit-controlling device, a manually operable circuit-controlling device, a base therefor, a control shaft rotatably mounted upon said base, a plurality of cams rigidly attached to the control shaft, means comprising one of the cams for ouerating said manually operable circuit-controlling device, and means comprising another of said cams for varying the operation of said thermal responsive circuit-controlling device.

13. In combination, a thermal responsive circuit-controlling device, a manually operable circuit-controlling device, a base therefor, a control shaft rotatably mounted upon said base, a plurality of cams rigidly attached to the control shaft, a bell-crank lever swingably mounted on said base and operatively associated with one of said cams, means comprising the bell-crank lever, the operatively associated cam and the control shaft for varying the operation of said thermal responsive circuit controlling device, means operatively associated with the bell-crank lever and thermal responsive circuit-controlling device for compensating for the ambient temperature, and means comprising another of said cams for operating the manually operable circuit-controlling device.

14. In combination, a thermal responsive circult-controlling device, a radiant heater operatively associated therewith, a manually operable circuit-controlling device, a base therefor, a control shaft rotatably mounted upon said base, a plurality of cams rigidly attached to the control shaft, a bell-crank lever swingably mounted on said base, said bell-crank lever being mounted intermediate the ends thereof and operatively associated at one end with one of said cams and rigidly attached at the other end to said thermal responsive circuit-controlling device, means comprising the bell-crank lever, the operatively associated cam and the control shaft for varying the operation of said thermal responsive circuitcontrolling device, and means comprising an other of said cams for operating the manually operable circuit-controlling device.

15. In combination, a bimetallic thermal responsive device, a base therefor, a circuit-controlling device operatively associated with said bimetallic responsive device, a bell-crank lever swingably mounted on said base and having one portion secured to said thermal responsive device, and means comprising the bell-crank lever for mechanically varying the effective angle of said bimetallic thermal responsive device.

16. In combination, a bimetallic thermal responsive device, a base therefor, a circuit-controlling device operatively associated with said bimetallic responsive device, a control shaft, a bellcrank lever swingably mounted on said base and operatively associated with the control shaft and having one portion secured to said thermal responsive device, and means comprising the bellcrank lever and operatively associated control shaft for mechanically varying the effective angle of said bimetallic thermal responsive device.

17. In combination, a bimetallic thermal responsive device, a base therefor, a circuit-controlling device operatively associated with said bimetallic thermal responsive device, a control shaft, a cam attached to the control shaft, a bell crank lever swingably mounted on said base and operatively associated with said cam and having one portion secured to said thermal responsive device, means operatively associated with the bell-crank lever and the bimetallic thermal responsive device for compensating for the ambient temperature, and means comprising the bellcrank lever, the operatively associated cam and the control shaft for mechanically varying the effective angle of said bimetallic thermal responsive device.

18. In combination, a bimetallic thermal responsive device, a base therefor, a radiant heater operatively associated with said thermal responsive device, a circuit-controlling device operatively associated with said bimetallic thermal responsive device, a control shaft, a cam attached to the control shaft, a bell-crank lever swingably mounted on said base, said bell crank lever being mounted intermediate the ends thereof, and operatively associated at one end with said cam and rigidly attached at the other end to said bimetallic thermal responsive device, and means comprising the bell-crank lever, the operatively associated cam and the control shaft for varying the effective angle of said bimetallic thermal responsive device.

EARL K. CLARK. 

